---
id: "CVE-2026-78334"
kind: "vulnerability"
aliases: ["CVE-2026-78334"]
title: "Apache bRPC: streaming RPC skips authentication, letting unauthenticated peers inject frames"
severity: "unknown"
cvss: null
epss: 0.00261
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["apache-brpc", "c++", "package", "self-hosted"]
not_affected_if: ["no-authenticator-configured", "no-streaming-rpc"]
published_at: "2026-10-21T12:17:23+00:00"
first_seen_at: "2026-10-23T21:57:28+00:00"
updated_at: "2026-10-25T05:02:35+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-78334", "first_seen_at": "2026-10-23T21:57:28+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-78334", "first_seen_at": "2026-10-24T13:15:54+00:00"}]
---

# Apache bRPC: streaming RPC skips authentication, letting unauthenticated peers inject frames

Apache bRPC before 1.18.0 does not run the authentication check on streaming RPC frames, so a remote peer can send streaming frames to a server that is configured with an Authenticator without logging in. A stream can also accept frames from a socket other than the one that created it when the frame carries the stream's id.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the bRPC version in use, for example with `grep -rn "BRPC_VERSION\|brpc" CMakeLists.txt` or the package manager lock file; versions below `1.18.0` are affected.
- Check whether the server sets `ServerOptions.auth` to an Authenticator and serves streaming RPC (`brpc::StreamCreate` or `StreamAccept`).

## Fix

- Upgrade bRPC to `1.18.0`.
- If an upgrade is not possible, apply the patch from https://github.com/apache/brpc/pull/3481.

## Timeline

- 2026-10-23T21:57:28+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-78334
- 2026-10-24T13:15:54+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-78334

## From the sources

Missing authentication in the streaming RPC path of Apache bRPC (version < 1.18.0) on all platforms allows a remote attacker to bypass server authentication and inject or deliver streaming frames, when a server is configured with an Authenticator.

Root Cause:
When authentication is configured, streaming RPC frames are consumed directly by the streaming parser (ParseStreamingMessage) and never pass through InputMessenger's authentication hook, so an unauthenticated peer can exchange frames without being authenticated. In addition, a server-accepted stream is bound lazily to the first frame that happens to carry its id, so a stream could accept a frame carrying its id from a socket other than the socket that created the stream.

Affected Scenarios:
A bRPC server configured with authentication that serves streaming RPC from an untrusted network, or a deployment where a foreign connection can impersonate a stream by id, can be made to accept unauthorized streaming frames.

How to Fix:
Upgrade bRPC to 1.18.0, which fixes this issue, or apply the patch in PR https://github.com/apache/brpc/pull/3481. 

Note:
The fix rejects streaming frames on server sockets when configured authentication has not completed, and keeps server-accepted streams bound to the socket of their creating RPC and rejects frames arriving from another socket. Authenticated streaming RPC behavior and the wire format are unchanged; only unauthenticated or foreign-socket frames are now rejected.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_